Electric generator.



\I F. NEW TON. ELECTRIC GENERATOR.

APPLlCATlON FILED JUNE 17. 1911. v

1,202,752. 2 Patented Oct. 24,1916.

2 SHEETS-SHEET 1.

Wa'fnejjas In W I 'v i I F. NEWTON. ELECTRIC GENERATOR.

APPLICATION FILED JUNE I7, 19H.

1,202,752; 4 Patented Oct. 24,1916.

2 SHEETS-SHEET 2.

5'A TUBA TE Wjfrzedsep 1720011702.

. Jf/orney UNITED STATES PATENT OFFICE.

FREDERICK NEWTON, OF LUTON, ENGLAND.

ELECTRIC GENERATOR.

To all whom it may concern Be it known that I, FREDERICK NEWTON, a subject of the King of Great Britain, residing at The-Rise, Leagrove, Luton, in the county of Bedford, England, electrical engineer, have invented new and useful Improvements in Electric Generators, of which the following is a specification.

This invention relates to electric generators, and its purpose is to regulate such generators, so that they yield a constant voltage or a constant current as the case may be in spite of variations in the speed of drive.

To this end the invention designs to utilize the different properties of saturated and unsaturated magnetic fields under varying exciting force.

More particularly defined the invention consists in .employing saturated and unsaturated magnetic fields to operate differentially upon the excitation of a generator in such manner as to keep that excitation at the value necessary to generate a particular E. M. F. or a particular current. I excite the saturated and unsaturated magnetic fields themselves by the constant E. M. F. or the constant current as the case may be.

A further object of the invention is to devise means for finally correcting the constant E. M. F. or constant current. I lead a correcting exciting current arounda few turns upon the unsaturated field circuit.

Examples of these various methods of carrying out the invention are illustrated 'in the accompanying drawings, in which- Figure 1 shows a constant voltage arrangement in which the difference between the fluxes in the saturated and unsaturated circuits operate upon an exciting armature; Fig. 2 is a constant voltage arrangement, being a slight modification of that shown in Fig 1; Fig. 3 is a diagram of the characteristic curves of the two magnetic fields; Fig. 4 shows Fig. 1' suitably modified for constant current purposes; and Fig. 5 is an arrangement corresponding to Fig. 1 in. which the difference between two magnetic fields acts upon the main armature.

In all the constructions illustrated the difierence between unsaturated and saturated magnetic fields is employed for exciting purposes. In Fig. 1 this principle is applied to the exciter of a main generator 41, 42, the connections being shown as suitable for constant voltage pur- Specification of Letters Patent. I Pate t d O t 24 1916 Application filed June 17, 1911.

Serial No. 633,809.

poses. The exciter field is made with two parallel yokes. One of these, 43, is designed to be saturated and theother 44 which, preferably, has an air gap in it, is unsaturated. The wlndings of the yokes 43 and 44 are connected in parallel or in series across the terminals of the main armature 42, and are so arranged as normally to circulate flux simply around the two yokes. The arrangement shown in Fig. 2 is slightly different in that the main'field 41 is shunted across the armatures 42 and 45 in series. In this arrangement, if the fluxes in the yokes 43 and 44 are equal there will be no flux through the armature 45. If the speed of the armatures 42 and 45-which are mounted upon a common shaft-should alter, the flux in 44 w1ll become less or greater than the flux in 43, and a balancing flux will pass in one direction or the other through armature 45. The manner of action of this arrangement 1s roughly as follows: When the two armatures are driven at normal speed the condition of the yokes 43, 44 is represented by the ordinate p in Fig. 3, that is to say the flux in yoke 43 will be equal to that in yoke 44, and no flux will pass through the armature 45. Therefore the winding 41 on the field of the'main generator will receive no correcting excitation current. Should the speed of the machine fall so that its condition is represented say by the ordinate 1 in Fig. 3 it will be clear that the flux in the saturated yoke'43 represented by the curve 5 in Fig. 3 will be much greater than that 1n the unsaturated yoke 44 illustrated by curve a in Fig. 3. Therefore a flux will pass in on direction through the armature 45 which will generate a current in the winding 41 to strengthen the field of the main generator. Correspondingly if the speed increases until the machine is working upon ordinate 1' of Fig. 3 the flux through the yoke 44 will exceed that through the yoke 43, and the current will pass in the opposite direction through the winding 41 and will tend to weaken the field of the main generator.

The main field 41 in Fig. 1 is simply connected across the armature 45. In this case, as in Figs. 4 and 5, the range of the machine as shown extends from the speed at which there is a maximum difference between the fiuxes to that at which they become equal, 1. from that corresponding to the ordinate g in Fig.2 to that corresponding to the ordinate p.

In Fig. 4 an arrangement similar to that in Fig. I is shown, except that the windings on the yokes i3 and 44 are series windings connected in the main work circuit instead of in shunt across the latter. As a consequence this arrangement is suitable for giving current of constant strength.

Fig. F 'llustrates a modification of Fig. 1 in which the armature 45 is itself the armature giving the main supply. It follows that the windings on the yokes 43 and 44: are connected in shunt across the brushes of the armature 45.

In all these constructions more exact' adjustment can be obtained by leading a correcting exciting current, which may be the exciting current of the exciting machine in the one case, and that of the main machine in the othe around a few turns upon the unsaturate field circuit, for example in Fig. 2 at 46 the unsaturated yoke of the exciter is wound with a few turns in series with the winding 41.

As explained, Fig. 4 shows Fig. 1 modified for a constant current, but in any of the arrangement above described if the saturated and unsaturated magnetic fields are excited by the current instead of by the voltage of the main machine they will cause this current to be maintained at a steady value.

Though especially adapted for use with variable speed driving devices, as for example trains, or wind or water turbines, the machine forming the subject of the invention may be used as an ordinary generator for battery or line booster in central stations and be driven by a prime motor which runs at substantially constant speed. Its properties are then of value because it prevents alternation of generator output, or line pressure, or current, as the case may require, in connection with a fluctuating load.

I claim- 1. In electric generating apparatus, the combination with a generative armature, of saturated and unsaturated magnetic circuits, a source of excitation therefor, and means whereby the differences of the fluxes in the two circuits may be passed through the armature.

2. In electric generating apparatus, the combinationof an armature and field structure, saturated and unsaturated magnetic circuits, means for supplying an excitation to said field structure proportionate to the difl'erence of fluxes in said circuit, and means for supplying a similarly propor tional excitation to one of said circuits.

3. In electric generating apparatus, the combination with a field structure having saturated and unsaturated parts, of an armature cooperating with said field structure, windings on said saturated and unsaturated parts, means for exciting the same, and a with said field structure and poles, driving means for said armature, and means for exciting said field structure.

5. In electric generating apparatus, the combination of a generative armature, saturated and unsaturated magnetic circuits, a source of excitation therefor, windings around said circuits in connection with said source, and means whereby the differences of the fluxes in the two circuits may be passed through said armature.

6. A variable speed electrical generating apparatus, comprising a main generator and a regulating generator ,therefor, comprising saturated and unsaturated parts, and pole pieces receiving the diflerences of the fluxes of the saturated and unsaturated parts, of means for exciting said regulating generator, from said main generator, said means exciting said parts to equal strength when the glenerating apparatus is driven at normal spee a 7. In electric generating apparatus, the combination of an armature, saturated and unsaturated magnetic circuits, a source of excitation thereof, windings around said circuits in connection with said source, an external circuit connected to said armature, a winding on one of said circuits in series with said external circuit, and means whereby the difierence of the fluxes in the two circuits may be passed through said armature.

8. In electric generating apparatus, the combination of an armature and a field structure having saturated and unsaturated portions, means for exciting said portions so as to maintain a main flux in proportion to the difference of the fluxes-in said saturated and unsaturated portions, and means for supplying to one of said portions an auxiliary excitation.

9. In a variable speed electrical generating apparatus, the combination of a field structure comprising saturated and unsaturated parts and pole pieces receiving the difference of the fluxes of the saturated and unsaturated parts, of means for exciting said parts to equal strength, when the generating apparatus is driven at normal speed.

10. In electric generating apparatus, the combination of an armature, means for collecting current therefrom, a saturated mag netic circuit, and means for exciting the name to this specification in the presence same tending to pass flux through said arof two subscribing witnesses.

mature and an unsaturated magnetic circuit having means for exciting the same, robbing FRED NEWTON 5 said armature of a portion of the flux pro- Witnesses:

duced by said saturated magnetic circuit. A. E. ODELL,

In testimony whereof I have signed my H. W. K. JENNINGS. 

